Sump assembly

ABSTRACT

The present invention involves a flexible annular member passing through a wall opening. The flexible annular member is positioned about a conduit passing through the wall opening to enable the conduit to pass through the wall at an angle up to and even greater than 30°. Another embodiment of the present invention comprises a flange type riser and base connection involving the location of the entire sealing assembly within a chamber base/riser section.

This application is a divisional of U.S. application Ser. No. 07/718,436filed in Jun. 26, 1991, now abandoned. This application is also acontinuation-in-part of patent application Ser. No. 07/555,210, filed onJul. 18, 1990, now abandoned, wherein the entire disclosure of which isincorporated by reference herein.

BACKGROUND OF THE INVENTION--CONTAINMENT SUMPS

Containment sumps are typically found at fuel service stations wherebythey are installed below the surface to provide a means of access to theunderground piping connections, submersible pumps, leak detectionsensors, fire extinguisher and other plumbing components usually foundconnected to the top of underground storage tanks or under fueldispensing units. There are generally two types of containment sumpswhich are similar in purpose but different in design. The first type, iscommonly referred to as a "tank sump" which is installed and connectedto the top of an underground storage tank. The second type is commonlyreferred to as a "dispenser sump", which is installed under a fueldispensing unit.

Containment sumps are multi-purpose in function: 1. They provide a meansof surface access to equipment, plumbing and miscellaneous devices,installed underground. 2. They provide a means of ground isolation forcontained components to prevent corrosion and decay. 3. They provide ameans of secondary containment for those contained components whichhandle hazardous liquids. 4. They perform as a collection sump fordouble wall piping entering the sump. Each of these functions will beillustrated and described in detail in this document.

In recent years there has been a national mandate to protect our groundwater from hazardous liquid contamination. As a result, there has beenfederal, state and local legislation created throughout the countryrequiring stringent regulations on the manner in which hazardous liquidsare stored and piped in underground applications. These new regulationsrequire the replacement of leaking underground storage units, storagetanks and associated underground piping. These regulations have alsoestablished new design criteria to prevent future tanks and piping fromleaking into the environment.

PRIOR SUMPS

Prior to any environmental regulations, there was no concern aboutinstalling a tank sump under the street manhole which provided access tothe tank and its pump and plumping components. All that was necessarywas to provide a barrier to prevent the surrounding backfill materialsfrom entering the area directly below the street manhole. This wastypically accomplished by installing a short section of large diametercorrugated pipe that was open at the top and bottom.

When fiberglass underground storage tanks entered the market, some yearsago, a problem arose when the unsecured corrugated pipe sections beganto damage the top of the tank due to tank and ground movement. It was atthis time that there was some attention given to designing a backfillbarrier which would not damage the tank. The fiberglass tankmanufacturers introduced a flange mounted backfill barrier which wasdirectly connected to the tank. At this time there was no thought tokeeping out water or containing leaking product. Therefore, noprovisions were made for sealed pipe and conduit entries or keeping outsurface water from leaking down through the street manhole.

In recent years these backfill barriers were replaced withenvironmentally safe tank sumps. These sumps addressed the need of beingliquid tight and being made of materials that were corrosion resistantand chemically compatible with the liquid products being stored. The newsumps also featured, enclosed bottoms, pipe and conduit seals, watertight tank adapters which provide connections to the tank. The tankadapters' two piece construction allowed for easier installation in deeptank burials. These new tank sumps were far from being a good design,they experienced leaking pipe and conduit entry seals, and weredifficult to install. Many of these sumps have collapsed due to externalbackfill and high groundwater pressure because of their structuraldesign. Most of these sumps are made of rotationally molded polyethyleneor glass reinforced plastic (fiberglass), both being a non-corrosivematerial.

DISPENSER SUMPS

With the introduction, of a new environmentally safe tank sump, has comethe development of a new type of sump called the "dispenser sump". Thesumps are of a different design but serve a similar purpose. They areinstalled under the fuel dispenser to provide a means of secondarycontainment for the dispenser plumbing and the underground pipingconnections located directly below the dispenser. These dispenser sumpsare available in both shallow and deep versions.

Subterranean piping systems, which are typically found at servicestations, connect the remote underground storage tank to one or moreabove ground fuel dispensing units. At each of these connectionlocations are found access enclosures which provides surface access tothese piping connections and other equipment such as a tanks' pump,valves and other plumbing devices.

The underground storage and fuel dispensing system has been determinedto be a source of environmental pollution, as well as a safety hazardbecause of product leakage into the surrounding earth. All components ofthat storage and dispensing system should be designed in such a mannerthat they prevent any leakage into the environment. Access enclosureslocated at the tank and under the dispensing unit provide a means ofsecondary containment for part of the entire system.

These access enclosures should be of such a design that they are liquidtight preventing ground and surface water from entering the enclosure,and containing leaking product from escaping the enclosure into thesurrounding environment. They should also be made of a material which isresistant to corrosion and deterioration, They shall be of sufficientstrength to withstand external pressure from surface loads, backfillpressure, and high ground water pressures. They shall also be designedand installed so that they flex or shift in such a manner that they donot damage the top of the tank as a result of tank, ground or surfacemovement. They should provide a means of effectively sealing all conduitand pipe penetrations into the sump. They shall provide a mean forliquid tight and secure connections to the tank and dispensing island.

PRIOR SEALING PRODUCTS

There are a number of products available which provide a means ofeffectively sealing all conduit and pipe penetrations into the sump.These products meet many of the above design requirements but for onereason or the other are deficient.

One of the areas in which these sumps are deficient is in the manner inwhich they deal with pipe and conduit entries into the sump. The natureof the problem is that pipe and conduit do not always enter or exit thesump in a head on direction. Because of the congested plumbingconfigurations inside the sump the exit direction of the pipe or conduitis many times at an angle in relation to the sump wall. Angled entriesand exits present a difficult installation problem and often make itimpossible to achieve a liquid tight seal using conventional pipe andconduit seals.

Different manufacturers offer a variety of seals and sump configurationswhich address pipe and conduit penetration. The most popular type ofseal being used is a rubber grommet which is available in a variety ofpipe and conduit sizes. This allows a hole to be drilled in any desiredlocation of the sump wall accommodating a pipe or conduit. Theeffectiveness of this product depends on a clean and even hole beingdrilled in the sump wall and the pipe or conduit entering and exitingthe sump in a head on direction. Many of the sumps that are leakingtoday are fitted with these type of seals. Once installed and buried itis virtually impossible to fix a leaking grommet.

Another manner of sealing pipe and conduit entries is to provideintegral molded cuffs in the sump located in fixed locations on the sumpwall. These cuffs generally face inward so that they are accessibleafter burial. The problem with this type of design is that they fix thelocation of all pipe and conduit entries or exits. This means theexternal pipe and conduit routing layout must be exact, and the internalplumbing configurations inside the sump must be designed in such amanner that the pipe and conduit exit at these fixed locations. Theseinternal cuffs are rigid and therefore do not allow for angled pipe andconduit exits. Another problem with these fixed internal cuffs is thatthey must be very large in diameter to accommodate a variety of pipe andconduit diameters. There are three types of internals cuffs available ondifferent types of tank sumps. The first type of cuff is available onfiberglass sumps and are designed to be sealed to fiberglass piping bymeans of applying a thermoset resin and glass matting. The second typeof cuff is available on rotationally molded polyethylene sumps aredesigned to seal the pipe or conduit by means of a rubber seal and bandclamp. The third type of cuff is available on steel sumps and use arubber reducer boot to seal from the outside of the cuff down to theoutside of the pipe or conduit.

Another area of the sump which has caused some concern in the past isthe sump cover which is designed to keep surface water draining downfrom around the street manhole and getting into the sump. Most sumps doan effective job in shedding this dripping water from above but are noteffective in a wet hole application where there is high ground waterthat can seep into the sump from below.

OBJECTS OF THE INVENTION

In view of the foregoing it is an object of the present invention toprovide a flexible pipe entry seal arrangement that will enable thepassage of a conduit or pipe through a wall opening, eitherperpendicular to the wall opening or at an acute angle of up to 15° ormore with respect to the wall opening;

Yet another object of the present invention is to provide a flange typeriser and base connection which enables the establishment of afluid-tight arrangement between a chamber base and a riser section thatresults in a completely fluid tight, mechanical seal that is locatedcompletely inside and not outside; does not need to be welded and isaccessible after installation;

The foregoing as well as other objects of the invention are achieved aswill be set forth below.

BRIEF DESCRIPTION OF THE FLEXIBLE PIPE ENTRY INVENTION

The flexible pipe entry seal arrangement of the present inventioninvolves the combination of a conduit passing through an opening in awall having an outer and inner surface. The invention comprises flexibleannular means positioned about the conduit for a substantial length ofthe conduit, the flexible annular means being made of a flexiblecorrosion resistant material and having a conduit engaging section. Theinvention further comprises flange means engaging an outer surface ofthe wall and bolt means associated with the flange means to hold theflexible annular means in position in engagement with the wall opening,wherein the wall opening is wider than the conduit whereby the conduitmay pass through the wall opening at a position other than perpendicularto the wall, of up to a 30° angle or more with respect to the wall.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the various figures of the drawing wherein likereference characters refer to like parts.

FIG. 1 is an elevational view showing a conduit (pipe) which can passthrough a wall at an angle up to and even greater than 30° and wherein aflexible pipe entry seal arrangement is being utilized;

FIG. 2 is sectional view showing significant internal parts includingthe flexible pipe entry seal arrangement;

FIG. 3 is an enlarged sectioned view of the flexible pipe entry sealarrangement;

FIGS. 4a-4f contain six views showing basic installation instructionsfor the flexible pipe entry seal arrangement;

FIG. 5 is an elevational view showing a conduit (pipe) which can passthrough a wall at an angle up to and even greater than 30° and wherein aflexible pipe entry seal arrangement is being utilized;

FIG. 6 is a sectional view of FIG. 5 showing significant internal partsincluding the flexible pipe entry seal arrangement;

FIG. 7 is an enlarged sectional view of the flexible pipe entry sealarrangement of FIG. 5;

FIGS. 8a-8f contains six views showing basic installation instructionsfor the flexible pipe entry seal arrangement;

FIG. 9 is an elevational view with portions broken away to show theflange type riser and base connection and the riser and cover seal usinga rib riser with O-ring;

FIG. 10 is a view related to FIG. 9.

Referring now to the various figures of the drawing wherein likereference characters refer to like parts, there is generally shown inFIG. 1, an embodiment of the flexible pipe entry seal arrangement of thepresent invention wherein the conduit or pipe 12 passes through anopening 14 (FIG. 2) in a chamber wall 16 at approximately a 30° anglewith respect to the wall.

The flexible pipe entry seal invention is shown in more detail in FIG.2. The pipe 12 is fixed with the flexible annular member 18, which asshown in FIG. 3, comprises a pipe engaging section 20 and an outerpositioned flange 22 which is preferably coated with an epoxy or othercorrosion resistant material. It is preferred that the flexible annularmember 18 be comprised of a corrosion resistant compressible materialsuch as a Buna-N rubber.

As shown in FIG. 3, the pipe engaging section 20 has an internaldiameter in the preferred embodiment of 2.375 inches. This permits thepipe engaging section 20 to fit relatively loosely about the outersurface of a typical two inch pipe 12.

A band clamp 24 (FIG. 2) with tightening nut 26 is provided to securethe annular member 18 about the pipe 12. The tightening bolt has athreaded stem (not shown) which engages a threaded hole in an associatedtab which has the effect of tightening or compressing the exterior ofthe pipe engaging section 20 of the annular member 18 tightly againstthe outer surface of the pipe 12.

As further shown in FIG. 2 the flange 22 is tightly secured against thechamber wall 16 by means of a series of nuts and bolts 28 (two shown).Also, the nuts and bolts 28 are provided in order to secure acompression ring 30 to both the flange 22 and then to the chamber wall16 and a further studded flange as shown in FIG. 2.

The installation of the flexible pipe entry seal arrangement of thepresent invention is further shown and described in FIGS. 4A-F. As shownin FIG. 4A, a drill 40 or other device is used with a preferablydisc-like template 9, having a 3/16" or 1/4" central guide hole (notshown) and the proper number and size holes around its circumferencewhich correspond to the number and size of the nuts and bolts 28 to beused to secure the flexible pipe entry seal to the wall 16.

The template 9 is placed on the wall 16 as a guide to create theappropriately size and number of openings. The central guide hole of thetemplate 9 is placed approximately at the center of the opening 14 (FIG.4E) through which the pipe will eventually pass. The drill 40 is thenused to create a pilot hole (not shown) through the wall 16, by drillingthrough the hole (not shown) in the template 9. After the pilot hole iscreated, the template 9 is temporarily secured to the wall 16 by use ofa typical nut and bolt. Thereafter, as shown in FIG. 4A, the first hole8 is drilled into the wall 16 by drill 40. After the first hole 8 isdrilled, it is preferred that a bolt (not shown) be temporarily placedtherethrough to prevent rotation of the disc template 9 while the otherholes are drilled. After the remaining number of holes to be drilled arecomplete, the template 9 and associated temporary nuts and bolts may beremoved from the wall 16.

As shown in FIG. 4B, a hole is cut or drilled in the wall 16, forexample, in one embodiment, a hole having a 4.5 inch diameter. It shouldbe readily apparent to those skilled in the art that the proper sizedhole depends upon the diameter of the proposed conduit and the propersized annular member 18.

Although the conduit passage hole may be made in any suitable fashion,it is preferred that the drill bit 44 be secured to the drill 40 havinga conventional hole saw 42 also attached thereto. Thereafter, by placingthe drill bit 44 through the previously created pilot hole (not shown),the larger hole created by the hole saw 42 will be properly positionedon the wall 16.

As shown in FIG. 4C, after the opening 14 is cut in the chamber wall 16,the flange 22 and threaded members are placed on the outside of the wall16 and passed through appropriate openings created as shown in FIG. 4A.On the inside of the sump wall 16 is placed compression ring 30 withcomplimentary openings (not shown) to those created by the template 9and there are similar complimentary openings in the flange 22 (notshown). The openings (not shown) of the annular member 18 are thenplaced about the corresponding threaded members. The entire assembly istightened as shown in FIGS. 4D-F using conventional nuts and bolts 28and washers, which in the preferred embodiment are comprised of acorrosion resistant material.

Thus, the angle of entry of the conduit or pipe 112 can be varied up to30° or more depending upon the dimensions of the opening 14 in thechamber wall 16, the size of the annular member 18 and the size of theconduit 12.

The second preferred embodiment of the flexible pipe entry sealarrangement 110 of the present invention is shown in FIGS. 5-8. Thisdevice may be installed over flat, curved or irregular wall surfaces dueto its construction.

A method of installing the second embodiment 110 is shown in detail inFIGS. 8A-F, to be described in detail below.

As shown in FIG. 6, the device 110 is utilized to connect a conduit 112or pipe through an opening 114 in a wall 116 such as a sump chamberwall. This device 110 prevents or minimizes the leakage of any fluid orother materials from one side of the wall to the other as a result ofthe opening therethrough, e.g., from a chamber (not shown) to theexterior thereof while permitting the conduit 112 to pass through theopening 114 at an angle of from zero to thirty degrees or more.

As described in further detail below, the device 110 basically comprisesan flexible annular member 118 formed of a generally flexible materialsuch as Buna-N rubber and means for securing the flexible annular member118 to the wall. The flexible annular member 118 comprises a pipeengaging section 20 through which the pipe or conduit 112 passes and aflange 122, the annular member 118 being secured to the wall 116 so thatthe flange 122 is positioned on the interior surface of the wall 116 andthe pipe engaging section 20 extends through the wall 116 to itsexterior surface.

As shown in FIG. 6, the flexible annular member 118 is positioned withinthe opening 114 of sump wall 116 with the pipe 112 therethrough and theannular member 118 being secured to the sump wall 116 by at least, andpreferably six or eight, conventional, preferably corrosion resistantnuts 128A and bolts 128B. The pipe engaging section 120 of the annularmember 118 permits the pipe 112 to pass therethrough and yet providesflexibility in the angle at which the pipe 112 may pass through theopening 114 of the wall 116.

Additionally, the device 110 comprises an internal compression ring orcollar 134, described in detail below, which aids in fixedly securingthe annular member 118 to the sump inner wall 116 and minimizes anypotential leakage by applying and dispersing the pressure produced bythe nuts 28A and bolts 28B, alone or in combination with the washers132.

As seen in FIG. 7, the diameter of the opening 114 is larger than thediameter of the pipe 112 to provide the flexibility, when necessary, forthe pipe 112 to enter the opening 114 at an angle, while stillmaintaining a seal to prevent the leakage of fluids or other materialsdue to the opening 114. In the second embodiment, the angle shown isless than 30°however any reasonable angle even in excess of 30° mayutilized as shown in FIG. 8F.

As shown in FIG. 6, the pipe engaging section 120 is secured about thepipe 120 by use of the band clamp 124 contained within channel 121. Theclamp 124 may be tightened by tightening nut 126 with a conventionalscrew driver (not shown).

As shown in FIG. 7, each of the bolts 128B has a threaded portionterminating at a head 128C, which is preferably completely containedwithin the flange 122 of the annular member 18 to minimize or eliminateany corrosive effects upon the bolt head 128C. It should be readilyapparent to those skilled in the art that, if desired, the bolt heads28C need not be contained within the flange 122.

As shown in FIGS. 8A-F, the device 110 is preferably installed in thefollowing manner, although any suitable manner of installation ispossible.

As shown in FIG. 8A, a disc-shaped template 109 is placed against thewall 116 to assist the installer in making the appropriate holes. Inorder to facilitate this process, the template 109 has a central pilothole (not shown) which is approximately 3/16-1/4" in diameter. Thetemplate 109 also contains a series of circumferential holes (not shown)which correspond in size and number to the bolts 128B (FIG. 8C) whichwill secure the annular member 118 to the wall 116. The template 109 ispositioned on the wall 116 so that the central pilot hole (not shown)will be approximately at the center of the opening 114 (FIG. 6) to bemade in the wall 116, as described below.

As shown further in FIG. 8A, once the template 109 is properlypositioned, a drill bit 144 is attached to the drill 140, preferablymaking a 1/4 inch hole in the wall 116, through the central pilot holeof the template. After the pilot hole (not shown) is created in the wall116, the template 109 may be temporarily secured to the wall 116 by aconventional nut and bolt arrangement 135. After the template 109 issecured, the template 109 may be used to create the pattern of holes(not shown) in the wall 116 through which the bolts 128B (FIG. 8C) willeventually pass. It should be readily apparent to those skilled in theart that the pattern of holes appearing on the template 109 is dependentupon the size and number of holes used to secure the annular member 118to the wall 116.

To optimize the positioning of these holes, after the first hole iscreated using the template 109, one may temporarily place a nut and bolttherethrough (not shown) to prevent any slight movement or rotation ofthe template 109 as each successive hole is made. After completing theproper number of holes, the template and associated temporary nuts andbolts are removed.

As shown in FIG. 8B, a conventional hole saw attachment 142 is securedto the drill 140 having the drill bit 144 of Fig. 4A attached thereto.The drill bit 144 is positioned in the previously created central pilothole (not shown) in the wall 116 to aid in positioning the hole sawattachment 142. The hole saw 142 then creates the appropriate hole 114(FIG. 6). For example, a two inch diameter hole saw is utilized forconduit entries and a 51/4" diameter hole saw may be used for a pipeentry, although any suitable size may be utilized depending upon thecircumstances of use.

As shown in FIG. 8C, the annular member 118 with the bolts 28B havingthe heads contained within the flange 122, is positioned so that thebolts 128B pass through the proper holes 135. An internal compressionring 134 is then positioned on the side of the sump wall 116 as shown inFIG. 8C. In the preferred embodiment, the compression ring 134 iscomprised of a rigid, non-deformable material such as steel. Thecorresponding washers 132 (when utilized) and the nuts 128A arethereafter loosely installed on each of the bolts 128B. The compressionring 134 is positioned opposite the flange 122 of the annular member 118and aids in sealingly securing the annular member 118 to the wall 116and in dispersing the pressure exerted by the bolts 128B and nuts 128Aover a greater surface area by maximizing the surface contact betweenthe compression ring 134 and the wall 116.

As shown in FIG. 8D, after all of the nuts 128A have been looselythreaded onto the bolts 128B, each bolt is appropriately tightened.Although any conventional method of tightening may be used, it ispreferred that a torque wrench be utilized so that each nut is tightenedto about 60 inch pounds. Excessive tightening of the nuts 128A maydeform the annular member 118.

As shown in FIG. 8E, the appropriate sized pipe 112 or conduit isinserted into the pipe engaging portion 120 of the annular member 118.The band clamp 126 is installed about the channel 121 of the portion 120and is secured thereabout by tightening of nut 126. As shown further inFIG. 8F, the annular member 118 is flexible enough to permit angle pipeor conduit entries of zero to thirty degrees or more in relation to thewall 116.

Reference is now made to the flange type riser and base connectioninvention as shown particularly in FIGS. 9 and 10 (upper figure). Thisinvention relates particularly to a nonwater tight manhole and may alsobe referred to as a flange type riser and base connection or base sealjoint.

FIG. 9 shows a tank sump having a chamber base 52. There are alsoupwardly extending ribbed riser 54, preferably made of a polyethyleneplastic. The ribbed riser or riser section extends above the chamberbase. The present invention relates to the flange connection between theriser section and the chamber base.

As shown in both FIGS. 9 and 10 the riser section 54 has a first flange56 and the chamber base 52 has a second flange 58. An O-ring 60 ispositioned between the two flanges 56 and 58. Fasteners 62 extend fromthe space below the lower edge of the riser and into the chamber base. Anut 64 is provided to make the assembly fast.

As illustrated in the drawings, the bolt hole circle for the fasteners62 is of a generally greater diameter D_(f) than the diameter D_(r) ofthe tubular riser section. Further, the tubular riser section has a stepportion 54B of generally U-shaped cross section at its lower terminalend comprising as illustrated axially spaced first and second riserflanges 56 and 56A connected by an axial wall 56B.

As shown in FIG. 9 there are at least nine such fasteners. Also, theassembly does not have to be welded and is accessible afterinstallation.

The fasteners 62 which extend into the chamber base are relied upon tosecure the flanges 56 and 58 and the O-ring 60 in a fluid-tightarrangement. Thus, the entire sealing assembly is located within thechamber base/riser section. The net result is to achieve fluid-tightarrangement involving a completely mechanical seal that is locatedcompletely inside and not outside. Stated another way the fasteners 62do not pass from the outside to the inside. This avoids the possibilityof unwanted leaks.

Without further elaboration, the foregoing will so fully illustrate myinvention that others may, by applying future knowledge, adopt the samefor use under various conditions of service.

We claim:
 1. A sump assembly comprising:a hollow base having a bottomwall, an upstanding side wall and a circumferentially extending radiallyinwardly directed flange extending from the upper edge of the base; anelongated generally tubular riser section having a circumferentiallyextending radially inwardly directed flange at its lower terminal edgeconfronting and overlying the base flange; a cover mounted over the openupper end of the riser; seal means disposed between the confrontingfaces of the riser and base flanges; and a plurality ofcircumferentially spaced fasteners for securing the riser flange andbase flange together with the seal means interposed therebetween, saidfasteners engaging through holes located on a circle generally greaterin diameter than that of the tubular riser section.
 2. A sump assemblyas claimed in claim 1 wherein said seal means comprises an O-ring havinga circumferentially extending sealing surface located radially outboardof the circumferentially spaced fasteners.
 3. A sump assemblycomprising:a hollow base having an upstanding side wall and acircumferentially extending radially inwardly directed flange extendingfrom the upper edge of the base; an elongated generally tubular risersection having an outwardly directed step portion at its lower terminalend including at least one generally radial riser flange; seal meansdisposed between the confronting faces of the riser and base flanges;and a plurality of circumferentially spaced fasteners for securing theriser flange and base flange together with the seal means interposedtherebetween whereby said fasteners are disposed interiorly of the riserand base and at least partially within the step portion of the riser. 4.A sump assembly comprising:a hollow base having an upstanding side walland a circumferentially extending radially inwardly directed flangeextending from the upper edge of the base; an elongated generallytubular riser section having an outwardly directed step portion at itslower end including a pair of axially spaced first and second generallyradially extending riser flanges connected by an axial wall; seal meansdisposed between the confronting faces of one of the riser and baseflanges; and a plurality of circumferentially spaced fasteners forsecuring said one riser flange and base flange together with the sealmeans interposed therebetween whereby said fasteners are disposedinteriorly of the riser and base and at least partially within the stepportion of the riser.
 5. A sump assembly comprising:a hollow base havingan upstanding side wall and a circumferentially extending radiallyinwardly directed flange extending from the upper edge of the base; anelongated generally tubular riser section having an outwardly directedstep portion at its lower terminal end of generally U-shaped crosssection including at least one generally radially extending riserflange; seal means disposed between the confronting faces of the riserand base flanges; and a plurality of circumferentially spaced fastenersfor securing the riser flange and base flange together with the sealmeans interposed therebetween whereby said fasteners are disposedinteriorly of the riser and base and at least partially within the stepportion of the riser.
 6. A sump assembly comprising:a hollow base havingan upstanding side wall and a circumferentially extending radiallyinwardly directed flange extending from the upper edge of the base; anelongated generally tubular riser section having an outwardly directedstep portion at its lower terminal end including at least one generallyradial riser flange; seal means disposed between the confronting facesof the riser and base flanges; and a plurality of circumferentiallyspaced fasteners for securing the riser flange and base flange togetherwith the seal means interposed therebetween, said fasteners engagingthrough holes located on a circle generally greater in diameter thanthat of the tubular riser section.
 7. A sump assembly comprising:ahollow base having an upstanding side wall and a circumferentiallyextending radially inwardly directed flange extending from the upperedge of the base; an elongated generally tubular riser section having anoutwardly directed step portion at its lower terminal end including atleast one generally radial riser flange; seal means disposed between theconfronting faces of the riser and base flanges; and a plurality ofcircumferentially spaced fasteners for securing the riser flange andbase flange together with the seal means interposed therebetweenpermitting assembly of the fasteners interiorly of the base and riser sothat they are sealed from the ambient environment outside the sumpriser, said fasteners disposed at least partially within the stepportion of the riser.